The samples were blinded with no indication as to their source, and sent to nine laboratories. The study involved laboratories supported by several HHS agencies along with Abbott Laboratories, Abbott Park, Ill., GenProbe Inc., San Diego, and the Whittemore Peterson Institute (WPI), Reno, Nev.
The nine laboratories tested identical sets of the new blood samples for the XMRV/P-MLV nucleic acid, for replication of the virus (whether it reproduced itself in cells), and for antibodies to the viruses. Two labs, which previously had reported the association of XMRV with chronic fatigue syndrome, reported the presence of XMRV for some samples. However, the labs reported similar rates of finding XMRV in samples from patients with chronic fatigue syndrome and from healthy donors who were known to not have XMRV. Additional tests run in the same and other laboratories on the same samples did not find XMRV, strongly suggesting that these persons were negative for XMRV/ P-MLVs. This would be a sign that the few observed positive results represented false positives that is, the results indicated the condition was present when it actually was not.
To investigate the validity of testing techniques and to determine XMRV's potential impact on the blood supply, HHS formed the Blood XMRV Scientific Research Working Group in December 2009. The NHLBI leads the working group, which includes other HHS agencies including the Office of the Assistant Secretary for Health, NIH's National Cancer Institute (NCI) and the NIH Clinical Center, as well as the Centers for Disease Control and Prevention and the Food and Drug Administration. The current study is based on the working group's efforts to determine the best way to test blood samples for the virus.
Researchers used 11 nucleic acid, five antibody, a
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NIH/National Heart, Lung and Blood Institute